1,2-Diacylglycerol kinase of human erythrocyte membranes. Assay with endogenously generated substrate

1,2-Diacylglycerol kinase activity was measured in human erythrocyte membranes using an assay procedure in which the substrate was generated endogenuously, either by treatment with a bacterial phospholipase C or by incubation with Ca²⁺, which activates a membrane-bound polyphosphoinositide phosphodiesterase. The properties of 1,2-diacylglycerol kinase were broadly similar to those described previously, except that in the present work maximum activities were higher and there was evidence for a double pH optimum.